http://www.thehighroad.org/showpost.php?p=2610061&postcount=8
RCBS sells a die to produce .45 ACP shotshells that will cycle. Designed by E. C. (Ed) Harris, this die reduces shortened .308 Winchester cases (the .308 and .30-06 are indentical to the .45 ACP at the head.) The finished shell looks like a ball round -- with the "ball" being a reduced and curved forward section of the shell itself.
I've made a few of these up -- a lot of work!! -- and they function just fine.
Shotshells will not damage your barrel -- but may lead it if you use too many. My solution to leading is to remove the barrel, plug the breech with a vaccuum line cap (from auto parts stores) and fill the barrel with a 50-50 mixture of white vinegar and hydrogen peroxide. Pour the lead scum that forms down the drain, dry and lube as normal afterwards.